1. Field of the Invention
The present invention relates to an optical connector in which optical fibers are positioned and fixed and optical connection is realized by using guide pins in optical communication, and particularly to an optical connector in which connection guide pins and optical fibers are positioned and fixed by V-grooves provided in the optical connector.
2. Prior Art
FIG. 1 shows an end surface view of a conventional optical connector for multiple coated optical fibers, in which a substrate with V-grooves is subjected to insert-molding so as to be integrated with a molding resin portion.
A substrate 1 is prepared so as to provide optical fiber guide grooves 3 and two guide pin grooves 4 arranged on opposite sides of a group of the optical fiber guide grooves 3 on an upper surface thereof. An upper plate 2 is bonded over the optical fiber guide grooves 3 of the substrate 1 in such a manner that upper surfaces of the guide pin grooves 4 are left to be entirely opened. By use of a metal mold, molding guide pins are subjected to insert-molding within the guide pin grooves 4 so that a resin molding portion 9 is formed to cover the substrate 1 and the upper plate 2.
At the time of coupling, the optical fibers are positioned and held in the optical fiber guide grooves 3, the end surfaces of the optical fibers are polished, and then the guide pins 7 are inserted into two guide pin holes 6 formed through molding respectively so that the optical fibers are positioned and coupled with each other. The coupling loss was about 0.25 dB in average in single-mode optical fibers.
In the conventional optical connector shown in FIG. 1, the guide pins 7 inserted into the guide pin holes 6 respectively are pressed by the molding resin portion 9 into the guide pin grooves 4 of the substrate 1, so that highly-accurate centering can be realized. However, there has been a problem that the guide pin holes 6 may be transformed as shown by dotted lines 6' by generation of shrinkage distortion of the molding resin after insert molding, so that the V-contact operation force of the guide pins 7 can not be sufficiently generated to make it difficult to realize optical connector coupling having a low loss not higher than 0.1 dB in single-mode optical fibers.
FIG. 2 is a perspective view of another conventional optical connector for collectively connecting a plurality of coated optical fibers by using guide pins. An optical connector 50 is formed of epoxy resin through molding and has such a structure that optical fiber holes 5 are arranged in one row in the inside of the optical connector 50 and guide pin holes 6 to which guide pins 7 be inserted are formed on the opposite sides of the row of optical fiber holes 5. Reference numeral 12 designates an opening portion from which a person can view the condition where the optical fibers are being inserted into the optical fiber guide grooves during the manufacture. Optical fibers are positioned and fixed in the optical fiber holes 5 and guide pins 7 made of stainless steel are inserted into the guide pin holes 6, so that optical connectors 50 in opposition to each other are positioned and fixed while being guided by the guide pins 7 to thereby realize an optical coupling.
Such an optical connector 50 employs a method in which optical fiber core pins for forming optical fiber holes 5 and guide pin core pins for forming guide pin holes 6 are positioned with high accuracy in a metal mold, resin is poured in the metal mold to perform molding, and then the respective core pins are drawn out after molding.
However, the outer diameter of each of the optical fiber core pins is very small, about 0.130 mm.phi., and it becomes difficult to perform molding with high accuracy because the optical fiber guide pins 7 are apt to be bent as the number of the optical fibers becomes larger in producing a connector for multiple coated optical fibers. Further, resin moldings have swelling characteristic against heat and humidity so that the pitch and diameter of the holes are apt to be changed, resulting in a problem in attaining a connection loss of about 0.1 dB in average.